Stress and Strain Calculator

Find stress, strain and how much a rod or bar stretches under load, or work out Young’s modulus from a test.

What Do You Want to Find?
Tension or compression along the length.
Cross-Section
Fractions and decimals both work.
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PSI Stress
Area
Metric stress
Strain
Stretch
Modulus E
A36 Yield Check

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How to Calculate Stress and Strain

Stress is force spread over area. Strain is how much a part stretches compared with its length. Within the elastic range they're proportional, and the constant is the modulus of elasticity E (Young's modulus).

Stress σ = F ÷ A   Strain ε = ΔL ÷ L   E = σ ÷ ε
Stretch ΔL = F × L ÷ (A × E)

Strain has no units; it's often shown in microstrain (millionths) or as a percent.

Worked Example

Typical Modulus of Elasticity

MaterialE (Million PSI)E (GPa)
Steel29200
Stainless steel28193
Titanium alloy16110
Copper17117
Brass15103
Aluminum1069

Typical handbook values; alloys and tempers vary a few percent.

Tips

These formulas hold only below the yield strength. Past yield the part stretches permanently. Mild steel (A36) yields at 36,000 psi; compare your stress to the yield strength of your material with a safety factor. Long, thin parts in compression can buckle well below yield.